The version of Org on my system prompts for Number twice. We want to store the value in an associative list somewhere so that if Org encounters another prompt with the same text, it’ll use the stored value. Here’s a diff that’ll do the trick.

You might want to add fields to the record creation process in M-x bbdb-create. In addition to asking for name, company, e-mail address, addresses, phone numbers, and notes, you may want to make sure you remember to put in birthdates or other information. If you want to prompt for custom fields after the regular BBDB creation form, modify this simple example to suit your needs: